Polymers have come to be used in various fields not only as a general-purpose structure-forming material but also as a value-added type material having functions and performances of a high degree. This is followed by an increase in the importance of producing high molecular materials under precise design. Attentions are paid on silsesquioxane derivatives of a cage type having a dimethylsiloxy group as an organic-inorganic composite material containing silsesquioxane as an inorganic component. This is because they are expected to be applied to precursors of organic/inorganic hybrid materials, low dielectric materials, optical crystals and liquid crystal materials, and the reason therefor resides in that the above silsesquioxane derivatives have a structure close to silica and zeolite. Cage type silsesquioxanes in which a hydroxyl group (document 1), an epoxy group (document 2) or a methacryloyloxy group (document 3) is bonded to a dimethylsiloxy group are reported. So-called organic-inorganic composite materials of organic polymers and silsesquioxanes are prepared by making use of the above functional groups. The organic-inorganic composite materials can be obtained by radically polymerizing cage type silsesquioxanes having a methacryloyloxy group alone or in the presence of other acryl base monomers.
In order to optimize the functions of high molecular materials according to purposes, the molecular properties of a polymer and the properties thereof as a molecular aggregate have to be precisely analyzed, and this makes it necessary to use a polymer having a distinct structure. However, conventional organic-inorganic composite materials do not contain polymers in which a structure is controlled as an organic component including the composite materials described above. A large part of them is obtained by mechanically blending silsesquioxanes with organic polymers, and therefore it used to be very difficult to control a structure thereof as a molecular aggregate of a composite matter. Then, it has come to be tried to control a structure of a polymer by using a polymerization initiator. It is disclosed in a document 4 that an α-haloester group is a good polymerization initiator for styrene base monomers and methacrylic acid base monomers in living radical polymerization, but silsesquioxane derivatives having an α-haloester group have not been known to date.
Document 1: J. Am. Chem. Soc., 122 (2000), 6979-Document 2: Chemistry of Materials, 8 (1996), 1592-Document 3: Macromolecules, 29 (1996), 2327-Document 4: Chem. Rev., 101, 2921-2990 (2001)